Alameda High School's principal sent home a letter about the bathroom graffiti, saying in part "Despite our attempts, we have not been able to ascertain who created this graffiti or what their intentions were."

Parent Edwina Phillips said their first reaction was "Oh no. Here we go again. Some kid is troubled and is trying to let us know."

Meanwhile, in Sebastopol, school officials closed Analy High School after someone found threatening graffiti specific to Tuesday in a boys bathroom.